\begin{tikzpicture}[scale=0.4]
    \pgfmathsetmacro{\a}{4}
    \pgfmathsetmacro{\b}{3}
    \pgfmathsetmacro{\c}{5}

    \tkzDefPoints{0/0/A,  \c/0/B}
    \tkzInterCC[R](A,\b)(B,\a)  \tkzGetFirstPoint{C}
    \tkzLabelPoints[above=.5em](C)
    \tkzLabelPoints[below left](A)
    \tkzLabelPoints[right](B)
    \tkzLabelSegment[above right](B,C){$a$}
    \tkzLabelSegment[above left](A,C){$b$}
    \tkzLabelSegment[below](A,B){$c$}
    % \tkzDrawPolygon(A,B,C)

    \tkzDefSquare(B,A)
    \tkzDrawPolygon(B,A,tkzFirstPointResult,tkzSecondPointResult)

    \tkzDefSquare(A,C)
    \tkzDrawPolygon(A,C,tkzFirstPointResult,tkzSecondPointResult)

    \tkzDefSquare(C,B)
    \tkzDrawPolygon(C,B,tkzFirstPointResult,tkzSecondPointResult)
\end{tikzpicture}

